It powers on. ~5 mins later the monitors lose signal, USB ports and ethernet stops working. But the computer stays on. Can't restart or shut it down with the buttons either. Have to shut it down via the PSU.

Yup, tried everything. Also to restart it again I have to wait for a while. Everything stops working even when I'm in the BIOS. Different RAM, CPUs, GPUs, PSUs, BIOS'.. VRMs look ok as well.. Everything looks brand new.

Yup, tried everything. Also to restart it again I have to wait for a while. Everything stops working even when I'm in the BIOS. Different RAM, CPUs, GPUs, PSUs, BIOS'.. VRMs look ok as well.. Everything looks brand new.

Any chance you rocked your 'NB' heatsink to one side and broke the thermal pad contact? while its running for the 5 min before it breaks you can see the temp?

Yup, tried everything. Also to restart it again I have to wait for a while. Everything stops working even when I'm in the BIOS. Different RAM, CPUs, GPUs, PSUs, BIOS'.. VRMs look ok as well.. Everything looks brand new.

Any chance you rocked your 'NB' heatsink to one side and broke the thermal pad contact? while its running for the 5 min before it breaks you can see the temp?

I've already replaced the thermal pad on the NB earlier this year.. Temps were ok (or it's difficult to tell because no program shows the correct temps for the NB. It's way hotter when putting my fingers on it) but what it showed remained the same through those 5 mins. But the PSU has been very hot lately, even when I don't stress anything. Using a 530W now with the Asus mobo and it's not even close to warm.
Think I'll buy a Crosshair V Formula-Z next week. Have to use that tax money for something useful